Zoom Link： https://zoom.us/j/2763667254?pwd=b0JoMWNBVFN4c0JXcmI0L01tblIxQT09

Abstract

Collective dynamics arises in systems of self-propelled particles and plays an important role in life sciences, from collectively migrating cells in an embryo to flocking birds or schooling fish. It has stimulated intense mathematical research in the last decade. Many different models have been proposed but most of them rely on point particles. In practice, particles often have more complex geometrical structures. Here, we will consider particles as rigid bodies whose body attitude is described by an orthonormal frame. Particles tend to align their frame with those of their neighbours. A hydrodynamic model will be derived when the number of particles is large. It will be used to exhibit solutions having non-trivial topology. We will investigate whether topology provides enhanced stability against perturbations, as observed in other systems such as topological insulators. This talk is based on recent results issued from collaborations with Antoine Diez, Amic Frouvelle, Sara Merino-Aceituno, Mingye Na and Ariane Trescases.

Speaker

Professor Degond was trained at the Ecole Normale Supérieure in Paris and his first appointment was in Ecole Polytechnique in Palaiseau in 1985 as a Junior Researcher at CNRS. He was then appointed a full Professor in Ecole Normale Superieure of Cachan in 1990. He joined back the CNRS in Toulouse as a Senior Researcher in 1993, where he founded the Applied Math group, and holds a permanent position. He has been a Chair Professor in Applied Mathematics at Imperial College in the period 2013-2020, and a Visiting Professor in Mathematics afterwards.

He is interested in plasma physics, rarefied gas dynamics, semiconductor modeling, collective dynamics, decision making and self-organization in complex systems arising from biology and social sciences. His methods combine analysis, asymptotic theory and multiscale numerical techniques. He has been been an invited speaker at the 2018 International Congress of Mathematicians (ICM 2018). He was awarded the Jacques-Louis Lions prize 2013 of the French Academy of Sciences and a Royal Society Wolfson Research Merit Award holder in 2014-2018.